The company said it has reached agreement in principle with Boston-based insurer Harvard Pilgrim to offer the outcomes-based rebate arrangement and is also in active discussions with other commercial insurers regarding this offering.

Spark Therapeutics also said it's addressing budgetary concerns by working towards multiple solutions to allow installment payments over multiple years.

Luxturna was approved last month by U.S. Food and Drug Administration (FDA) to treat children and adult patients with confirmed biallelic RPE65 mutation-associated retinal dystrophy that leads to vision loss and may cause complete blindness in certain patients.

It works by delivering a normal copy of the RPE65 gene directly to retinal cells, leading these cells to produce the normal protein that converts light to an electrical signal in the retina to restore patient's vision loss.

Prior to this approval, the FDA greenlighted two other gene therapies that re-engineer people's own immune cells to treat blood cancers.

Both came with hefty price tags. Yescarta, a drug that treats certain types of large B-cell lymphoma, has a price tag of 373,000 dollars. Kymriah, a leukemia therapy, is similarly expensive at 475,000 dollars.